Know what the latest must-have product is in Japan? While it looks like they've gone mad and are shaving their wrists, they're actually saving the planet by switching off the air-con, and cooling down using freezing cold foam-spray.

Over 10 years ago, two Stanford University biologists had a similar idea with their prototype glove which cooled down Stanford athletes, as well as extinguishing fatigue. DARPA was reportedly so enamored with the idea that they started developing something similar. But like with so many innovations, what DARPA may be working on in sealed laboratories, the Japanese public have been buying for several years.

These icy-cold foam sprays have been around for a while in the East, but according to Japan Trends they've suddenly hit the mainstream, with overheating city-dwellers spraying the silly string-like hardening substance on their arms, around their necks and wrists, to cool down in their offices or on the subway. A list as long as your (cooled-down) arm of all the various cooling sprays can be read over at Japan Trends, though I must say I'm disappointed by the lack of Hello Kitty sprays. [Japan Trends]